| n order to establish baseline data for further studies on the physiological role of prostaglandins (PGs) in the colon, the PG profile and synthetic capacity of different tissue sources and subcellular fractions of the colon were defined and compared. Data from this study demonstrate: (1) different PG profile and synthetic capacity of tissue sources and subcellular fractions; (2) alteration of PG profile due to the variation of arachidonic acid (20:4n-6) availability. Thus, the outcome of experiments on the physiological role of PG in the colon may be determined, in part, by the tissue source and subcellular fraction selected for analysis. This study also suggests that the variation of substrate availability in physiological and pathophysiological processes may affect the PG profile of the colon. The next study was then undertaken to examine the effects of dietary fats and fibers on biomarkers (cell proliferation, fatty acids in phospholipids and PG synthesis) of colon carcinogenesis and the relationship between these biomarkers. Groups of 10 male Sprague Dawley rats were fed one of nine experimental diets for 3 weeks: 3 types of fat at 15 % by weight (beef tallow, corn oil and fish oil) x 2 types of fiber (pectin and cellulose) plus fiber-free as a control group. The pectin and beef tallow diets stimulated cell proliferation whereas the fish oil diets did not (p... |
